There are several objectives of this research. One is to develop chemical syntheses of certain complex molecules showing antitumor, antiviral or antibiotic activity of an exceptional sort. In order for such syntheses to be practical and sufficiently flexible to allow the production of a wide range of structural analogs, new synthetic reactions and methodology must be developed. A second goal, therefore, is to discover new synthetic principles and methods, in order to extend our capacity to effect syntheses of the most challenging type. In a most general sense we seek to extend the power of organic synthesis, upon which much of the progress of medicine ultimately depends and at the same time to achieve the synthesis of important substances. Another objective which at first sight seems different, but which is related, is the study of enzymic synthesis of complex molecules. Such studies should improve our understanding of nature's way of constructing complicated natural products. More importantly by the synthesis of molecules designed to inhibit the action of certain enzymes, it is hoped that medically useful compounds may be uncovered. Finally, it is our aim through these chemical studies to make significant contributions to medicine. BIBLIOGRAPHIC REFERENCES: Synthesis of Brefeldin A, Carpaine, Vertaline, and Erythronolide B from Nonmacrocyclic Precursors, E.J. Corey, K.C. Nicolaou, and L.S. Melvin, Jr., J. Amer. Chem. Soc., 97, 654 (1975). Synthesis of Novel Macrocyclic Lactones in the Prostaglandin and Polyether Antibiotic Series, E.J. Corey, K.C.Nicolaou, and L.S. Melvin, Jr., J. Amer. Chem. Soc., 97,653 (1975).